Thermally-controlled circuit breaker



Nov. 27 1923.

1,475,631 c. HERBST THERMALLY coNTRoLLED CIRCUIT BREAKER Filed Aug'. 15. 1921 Patented Nov. 27, 1923.

UNITED STATES PATENT OFFICE.

CHARLES HERBST, 0F CHICAGO, ILLINOIS, ASSIGNOR TO ALFRED HERZ,` 0F CHICAGO, ILLINOIS.

THERMALLYCONTBOLLED CIRCUIT BREAKER.

Application filed Angust 15, 1921, Serial No, 492,248.

larly as applied to water-heaters, the inven tion is not to be limited to such use,

lVhile the invention is particularly applicable to heating circuits, it is also valuable Jfor general control work of power, lighting and the like circuits.

Usually, thermally controlled circuit breakn ers are based upon the principle that excessive flow ot' current will create a rise in temperature, and by the employment of a fusi ble member, which is directly inserted in the line and subject to the current flow, the circuit may be easily interrupted as the fusible member melts. It is customary to insert a fuse in the line adjacent to the apparatus to be protected. The fuse melts upon an excessive flow of current and the circuit is opened and will not be closed again until the fuse is replaced.

Although. I rely upon a fusible member to control the breaking of the circuit, I employ the fuse as a controlling element for a switch or other current. interrupter. The t'usible element which I employ is not subject to the. tio.Y ot current, and in fact, has no direct relation to current flow.

I provide a thermally controlled element,

'inally controlled element registers an undue rise of temperature, the circuit is opened by the release of the switch, or other circuit controller.

It is to be recognized as an important feature of my invention that the thermally controlled element releases a switch, which normally tends to move, as for instance to open position, the switch being restrained from such movement by the thermally controlled element., and that the switch remains in such open position until the thermally controlled element is replaced. This replacement is made after the heating device has been cooled ofi. A steam table is employed in restaurants, on lunch counters, and the like for keeping food hot, and yet accessible for inspection. A number of various size pans for containing the food are set in 'openings at the top ot the steam chest; The lower portion contains water and is provided with one. or more wells, in the shape of cylindrical tanks, secured by a soldered seam to the bottomof the steam chest, and around these wells are wrapped heating elements. The water circulates in and out of the wells and is heated by the heating coils, part of which water is frequently drawn oil" for use, and

oftentimes, the level is caused to lower by evaporization.

If the water level is permitted to get so low in the steam chest and heating wells that the soldered joint between the flanges of the heating vessels and the bottom of the steam chest is exposed, the solder may melt and the vessel destroyed.

According to my invention, I provide a thermally'controlled element in the form of a fuse, which bears against the wall of the heater, and which is subject to the heat of the heating coil. This fuse is laced adjacent to the top of the water well preferably between the heating coil and soldered seam. so that lowering of the water level below the seam which is to be protected at once affects the fuse.

The fuse is in general part of the switch, which controls the heating circuit. The fuse is not related electrically to the circuit.

A base member is mounted near the water. i

permit a suitable portion to contact with the wall of the well, in order that the fuse will be subjected to the heat developed. The fuse melts' on an excessive rise of temperature and the switch blade therebyr being released moves to open position. The circuit is then interrupted until normal conditions return.

The invention is not to be limited to heating vessels of this character, as it may be applied to all kinds of electrical apparatus in which there is danger of overheating, whether those devices be fundamentally heating devices or power devices.

The description of the invention shall be directed particularly to the protection of the soldered seam in the heating vessel. But, the requirement may arise where it is necessary to protect other joints or parts from damage by heat. Hence, the protection extends not to the soldered joint solely` but to any part of the vessel or the whole vessel.

In the accompanying drawings:

Figure 1 is a vertical sectional view of a water heater or steam table;

Figure 2 is a front elevational view of the same on a reduced scale;

Figure 3 is a sectional view taken on line 3-3 of Fig. 1, looking in the direction of the arrows;

Figure 4 is a detail illustration of the thermally controlled circuit breaker as used in connection with a water heater;

Figure 5 is a side elevational view of the same; and

Figure 6 is a detail View of a clip for holding the Jfuse in operative position.

I shall irst describe the water heater A in general to make more clear the particular advantage my invention has as a thermally controlled circuit breaker and to what extent it may be used where it is desirable to control a circuit by the heat developed.

Referring to Figure 1, the water heater is shown in the 'form of a steam table 5. The steam table 5 comprises the base 2, the lower compartment divided by the wall 3 from the upper compartment or reservoir 4, which I term a steam chest. lin which steam is generated and retained. and a greater portion of the water is held. The warmingpots 6 are suitably retained in the top wall., and are partially submerged in the hot water and partially exposed to the steam. as is well known in the art. A faucet 7 is provided for the purpose ot drainingl the reservoir 4, or drawing ofi' a small quantity of hot water for use, which is replenished in any! suitable way, such as a connection leadingl to a suitable source of supply (not shown). A gauge 8 has also been provided to indicate the level of the water in the reservoir.

lin the lower compartment, veesel 9 is disposed, which "Vessel rn-y be suspended from the wall 3, so that the interior of the vessel has communication with the upper compartment 4;. This vessel 9 is provided with a rim 10 at the open end and secured preferably' b soldering, as indicated at 11, because of t e cheapness of such a joint. A air of heaters 12 and 13 are arranged to eat the heating vessel 9 to bring the liquid to a desired temperature. The heater 12 comprises a winding of a number of turns of fine wire, and the heat-er 13 comprises a winding of a number of turns of coarser wire, so that the Watta e consumed by the heater 12 is considerab y less than the wattage consumed by the heater 13. The windings 12 and 13 are wound upon the vessel with a layer of insulation interposed to prevent short circuiting of the turns. The windings are anchored to the heating vessel tl as by means of terminal bands 15, which are mounted between and at the ends ofthe windings, and which serve as electrical terminals and as securingr means. l

The heaters 12 and 13 are controlled by the switch 16, which is operated by means of a handle or knob 17 having formed thereon a pointer 18. A suitable plate or escutcheon 19 is carried by the protruding portion of lthe switch 16. The switch 16 has three positions which are indicated by suitable legends on the escutcheon 19, the first position being had when the heaters 12 and 13 are connected in the circuit in parallel relation. ln the next position, the switch 16 connects the low wattage coil in the circuit, while in the last position the switch disconnects both of the coils so that they are inactive. The circuit is completely broken and no heating takes place. A ilot light 20, which is mounted on a suitab e support is permanently connected across the termi nais of the low wattage heater 12. A. bulls eye or fresnel 21 is placed over an openingr in the base to indicate the condition of the 'pilot light 20. The lead wire 23, which may be connected to a suitable terminal, enters the base through a. suitable insulation 24.

The circuit is controlled by the thermally controlled switch25, which is automatically governed by 4the temperature of the heating vessel 9. A fusible member 26 is' interposed between the heating coil 12 and the solder seam 11, and is made to lie against the periphery oi the heating vessel 9, in order to be in direct Contact 'with the part to be protected iiroin too ,rrreatheating by the coil 12. As shown Figure el, the fuse may be disposed so as to ineke considerable sui-'face contact with the vessel 9. or a tangential contact may be 'found preferable. end of the :iusibl iber 26 is formed a bead 27, th .li be he the groove 'torniO do, of the clip 28. c

lll)

or otherwise fastening to the underside of the wall 3.. While this clip 28 is employed, it is possible t0 provide any form of holding means for this end of the fusible member 26. The opposite end of the fusible member 26 is provided with an eye 29 which receives a stud 30 carried at the free end of the switch blade 31. The surface of the stud is preferably roughened, so as to prevent the eye 29 from sli ping thereol. v

The thermal y controlled switch 25 is mounted and carried as a unit on the under side of the wall 3, preferably located adjacent to the heater 9 and readily accessible in case the fuse 26 is to be replaced and the switch reset. The mounting plate 32 is centrally raised by the provision of side flanges 33 terminating in outwardly turned ends 34, which ends34 provide adequate adhering surface for the soldered, or otherwise formed, joint with the wall 3. The switch blade 31 is pivotally carried by the bolt 35 on the mounting plate, with the necessary washers and lock nuts to keep the blade 31 properly mounted, provided, the lead 36 of the heating circuit being clam d thereon at the outer end. Thus, the bo t 35 is subject to the flow of current, and in order to prevent short circuiting through the mounting plate 32 an insulator sleeve 37 surrounds the bolt 35 where it passes through the plate 32. Plate insulation 38 is provided on each side of the lmounting plate32 so as to prevent the current from flowing therethrough from the washers 39. This plate insulation may be made out of mica, or other suitable material. A terminal 40, of an type, is mounted on the plate 32 in suc relative osition as preferably to engage the switch blade 31 near the outer end. The other lead 41 of the heating circuit is properly clamped thereto. The mounting plate 32 is likewise insulated from the current at the terminal 40.

The switch blade 31 is normally closed, but tends to move to open 4position by the spri'ng 41. The blade is restrained from such movement by the fusible member 426 until the temperature of the heater, at the point of. Contact, rises to a predetermined point, whence the fuse melts and the switch opens. The spring 41 is anchored upon the bolt 42 carried by the base 32. The short leg of the spring 41 bears against astop bolt 44, which stop bolt is provided to limit the movement of the switch blade 31 when being opened.

From experience, it has been found advisable to insulate the spring 41. Consequently the long leg thereof has been fastened to the blade 31 in such a manner as not to come in contact With the live portion of the blade. The free end of the blade 31 is turned down, as indicated at 45, in order to carry properly the stud 30. It will be seen from 5 .that this stud 30 is insulated from the turned down portion in a manner similar to that of insulatin the bolt 35 relative Vto the base 32. Hence, te bracket 46, to which the spring 41 attaches, is not subject to the flow of current.

Thus, it is to be noted that as the fuse 26 is located adjacent to the joint 11, it is subject to the heat of that portion of the vessel, and therefore, the switch 25 will be actuated to render the heating coils 12 and 13 inoperativel as soon as the temperature builds up to a point beyond safety for the joint. The fuse 26 being directly above the heating coil 12 will be governed directly by the heat thereof so that, if the water level recedes below the area adjacent the fuse 26, the temperature of that portion of the vessel will rise and act directly upon the fuse lbefore reaching or affecting the soldered seam.

The operation of the device is as follows:

Assume, that the device has been in operation for a considerable period of time and the water level within the steam chest is caused to lower, either by evaporation or by drawing olf a. small quantity for use, below the seam 11 in the heating vessel 9. The water will no longer keep this portion of the heater cool and as a result, the heat from the coil 12 or coil 13 will act directly thereon. It will be noted that the fuse 26 lies in the path of the heat which tends to travel to' the joint 11 from either heating coil. When the coil 12 is active, it isv obvious that heat from this coil in travelin toward the seam 11, will encounter the use and melt the same. lll/Then the coil 13 is active, the heat which travels toward the seam 11 along the wall of the vessel, will first encounter the said fuse. The temperature will immediately rise to the temperature of fusion and cause the fuse 26 to melt, which releases the blade 31. The spring 41 being of sufficient strength, will cause the switch blade 31 to break the circuit between itself and the contact 40 by moving outwardly. This condition is indicated immediately by thegoing v out of the pilot light 20.

To restore the device to operation the pots 6 are removed and the heating vessel is permitted Ato cool. As soon as this is done and the surface against which the fuse 26 4bears cools suiiiciently, the device is inverted. The

fuse may then be replaced with comparative ease, for all that is required in the replacement is to substitute a new fuse member rovided at each end with means for facil1tating rapid connection. The device will then be in proper condition for further operation. After it is set up, cool water is fed into the steam chest until the proper level is reached, as will be indicated by the gauge 8. No other soldered joint of the device is affected by the loweringof the water level as the fuse is located so as to be aected immediately,

i et liest to seicl jeint that is, the heat is net permitted to trevei the Wells ci? the heater 9, and from there7 te ne trunsfei'iefi te the entire dei/'ice nefc'e melting the fuse 26g Frein the feiegeing descriptimi7 it is evident that my device has greet iuilitj7 es s. thermally controlled circuit breaker enel possesses certain advantages, as such, te en extent 'wher it may be adept/d te devices other than electi'ic witter heaters. The peint nt which the circuit breaker Wili sctuete, is dependent upon the temperstui'e et fusion of the meunier 2G. which, of course, may be determina-ble by the use te which the device is put.

I claim:

l. in combination, :L 'vessel having' a fu ble joint, e heating element fel seidv si 'esseL theimelly operable means for renderina-)r said heating element inactive, seid thermally operable ineens being disposed leetween the heating element and seid fusible joint and in contact with the vessei.

2. in cciniiinetien7 u vessel having s fi'usiliie joint,j e nesting circuit for heating;N seid vessei enel circuit bucales? disposed between seid nesting ciicuit und seil fusibile jeint7 emi in centect with the Vessei, seid circuit breekei being ccntielied l' conduction fer renflezuig the liesting circuit innetive.

3. )ln @nubinetien7 :t vcssei leaving n fusible joint, e nesting ciicuit fer heatingA seid vessel end e circuit breaker centecting with seid; vessel between the heating; cii'cuit :ind the 'fusible joint und centivelleci by ccnducticn cf heat te seid joint tei" iencleing tile heating circuit inactive.,

in combination, c nesting vessela e lic-ating circuit felt heating; seid vessel en s circuit bieelein eontuctin.) with the vessc. and ccntiellecl by cenduetien et heet the, to indepenently cf the cuiicent flew sr heating circuit foi' i'endeiing ssi circuit inactive 5. in ceinluintien7 e. heating" vessel neving e fusible j uint, e heating cicuit :ten liesting. Seial Vessel, a. switch in seid circuit, spring ineens tending te open, seid switch sind tlieiiinully epeisbie ineens independent cicuirrent ties-7 in said circuit ini' liclelingseid switch closed, scifi themneliy operable ineens being disposed between the heating circuit und seid fusible joint end in contest 'with the vessel and being centircilel by cenductien of liest seid joint for releasing' seid spring Ineens to permit opening of' said switch.

iin combination7 e heating vessel, a nesting circuit fer heating seid vessel, a switch in seid circuit9 seid switch4 having' a movable switch niemeer, Ineens tending' to nieve seid member to open position, and a fusible link fixed et ene enel und connecte-:i seid movable switch meznbel`7 to restrain cpening of seid member, said fusible link contacting with seid vessel and lbeinj ccn- 'trclled by heet conduction thereto Ier reiessin the switch member tu permit opening of sein switch.

7 in combination, e casing, e heating vessel carried by said casing, n nesting cir cuit for said heating vessel, e switch mounted adjacent to seni vessel en seid cssing, ineens for normally tending te nieve seid switch te open position, and e therineliy controlled element in operable relaticn with seid switch extending to seid `sessel and disposed se es te be subject te the liest developed. v

lin combinaties1 nv casing, s inenting Yvessel cerried by seid. easing, n. heating; circuit for seid nesting vessel, a. switch clispesecl sdjncent te sail circuit, incl e ther-- inuilj/ ccnti'ciiei'i element fer Contreiling tile cpeietien ci switch., seid element tcneiing tc seid vessel su es te centuct tlieicwith between seid cii'cuit une; said casing'.

9, in cninliinetien, a cssing, e nesting carried by seid cesingv' e switch flispesccl adjacent te seit?. circuit, ineens acting te heid seid switch in open pcsitien, e thetneily eentielied element iestmining said movement said tl'iermnlly contelied eieinent being "euible enti independent ef seid ein enit une iynig se es te melts peripheral cen- Wi i1 sei nesting vessel,

lill

iin cemliinstiom vessel listing superceniuurtinents divided by e Well, a D ifcssei suspended trein seid Well, a cuit lievi-ng e. heating ceii sniieuncling nesting vessela e switch in seid circuit,

f el including' e switch n'ieiniirer jini ily' mounted. upon said well, means t te @pen seni switch and s fusible lint.; ti-m ut one end and eufztencling` ineen.- tact with seid vessel envi cennected et its cppesite end te seid switch member for heidingy seid meinten clcsedh in Witness Wliereef I hereunto subscribe my name this 9th day of Au ust, 1921.

CHARL i S HERBST- Gli 

